1. Field of the Invention
The present invention relates to a liquid ejection apparatus, an ejection control method for a liquid ejection apparatus, and an inkjet apparatus, and more particularly to technology suitable for preventing continual ejection from an ejector (a droplet ejection mechanism) while it suffers a control error due to a breakdown in a circuit control device, or the like.
2. Description of the Related Art
A liquid ejection head such as an inkjet print head includes a plurality of ejectors to eject droplets of liquid. Each ejector is constituted of: a nozzle forming an ejection port, through which droplets of the liquid are ejected; a pressure chamber, which contains the liquid and is connected to the nozzle; and a pressure generating element, which applies ejection energy or pressure to the liquid in the pressure chamber. The pressure generating elements arranged correspondingly to the respective ejectors are connected to a circuit control device through electrical wiring. The circuit control device includes a plurality of switches, which can be caused to close and open in accordance with external signals. The pressure generating elements are connected respectively through the switches to a drive circuit. By controlling the closing/opening states of the switches connected to the pressure generating elements, application of a drive voltage to the pressure generating elements is controlled, and the ejection of droplets from the nozzles is thereby controlled.
In such a composition, there are cases where a part of the circuit control device breaks down and a part of the ejectors becomes uncontrollable, for some reason. For instance, a fault can occur in which a switch connected to a pressure generating element remains closing in spite of the fact that an external control signal is applied to open the switch. In this case, unnecessary ejection is continually performed from an ejector connected to the switch suffering the fault.
In order to solve such problems, Japanese Patent Application Publication No. 2006-142504 describes a method which disables ejection by disconnecting a wire which connects to an ejector that has an ejection abnormality. As a concrete means of achieving this, a method of cutting the wire by applying a laser from a nozzle face side of a liquid ejection head is described. However, this method can be implemented only to a case where the wire connected to the ejector having an ejection abnormality is situated close to the nozzle plate. Furthermore, when an ejection abnormality has occurred in a print head that has been installed in an inkjet apparatus, the aforementioned method cannot be employed unless the print head is removed from the inkjet apparatus. Supposing that a composition is adopted in which a laser generating apparatus is appended to an inkjet apparatus, then the costs rise accordingly.